Applying composition control to improve the mechanical and thermal properties of Zr-Cu-Ni-Al thin film metallic glass by magnetron DC sputtering

This study is intended to investigate the amorphicity region of Ni + Al content in Zr-Cu-Ni-Al thin film. The thermal and mechanical performances of Zr-Cu-Ni-Al thin film metallic glass (TFMG) are also addressed. By adjusting target power, thin film metallic glass with various (Zr + Cu)/(Ni + Al) ratio were fabricated. The composition of the Zr-Cu-Ni-Al thin films was analyzed by field emission electron probe micro-analyzer (FE-EPMA). Via Grazing Angle X-Ray Diffractometer (GIXRD), all Zr-Cu-Ni-Al thin films show the hump peak, implying the amorphous feature. To further identify the amorphous characteristic, a differential scanning calorimetry (DSC) is used and the amorphicity region of (Ni + Al) in Zr-Cu-Ni-Al thin film is as wide as 54 at.%. Besides, the glass transition temperature Tg, for all Zr-Cu-Ni-Al TFMGs are above 700 K, and the △ T ranges from 50 K to 70 K. With the aid of nano-indention, hardness and elastic modulus were measured in which the hardness reaches 7.5 GPa for Zr23Cu23Ni27Al27 TFMG. The value of △ T increases with (Ni + Al) contents in Zr-Cu-Ni-Al TFMG across the whole amorphous region, indicating that the thermal stability is improved and higher hardness is thus achieved. For a better intrinsic viewpoint, the average interatomic distance is calculated. The calculated distance gets closer with Ni + Al content, which might result from the increase of short range order (SRO) structure with good thermal stability. From the positive correlation of elastic modulus and Ni + Al content, the improved hardness is explained in the viewpoint of energy. In summary, the thermal and mechanical performances of Zr-Cu-Ni-Al TFMG with 54 at.% (Ni + Al) content are among the best in the class of Zr-Cu-Ni-Al metallic glass, implying that Zr-Cu-Ni-Al TFMG with improved performance can be fabricated in lower cost.